1. Field of the Invention
The present invention relates to an image processing apparatus and an image forming apparatus, and more particularly to a technology of executing a gradation processing to character data.
2. Description of the Related Art
In an image forming apparatus in which an image is formed on a recording sheet by an electrophotographic process using image bearing members such as a photoconductive drum and a transferring belt, when a character having a relatively small size (font size) is printed to have a halftone, an edge portion (end portion) and an isolated portion (such as a point in one character, and the like) may not be depicted and the character cannot be discriminated, so that it becomes difficult for a user to read the character.
In view of the above-described problem, a patent document (Japanese Patent Unexamined Publication No. 2004-306555) discloses the following technology. Firstly, it is determined whether the character size is equal to or smaller than predetermined points. When the character size is greater than the predetermined points, it is determined that the character size is greater than a normal size and then a screen processing for a normal size is executed to data constituting the character. On the other hand, when the character size is equal to or smaller than the predetermined points, it is determined that the character size is smaller than the normal size and then a screen processing for a small size, which makes a gradation of a character be greater than that achieved by the screen processing for a normal size, is executed to data constituting the character. In other words, the patent document discloses a technology of executing an image processing in accordance with the screen processing for a small size or the screen processing for a normal size to a whole character.
However, according to the technology disclosed in the patent document, the screen processing for a small size or the screen processing for a normal size is executed to a whole character, so that it is likely that a character which does not maintain a user's desirable gradation level is to be printed. Further, the screen processing for a small size is not applied to a character having a font size greater than the predetermined points, so that it may cause a situation where an edge portion (end portion) and an isolated portion are not to be depicted, depending upon a font size of a character.